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what is the only known causes of periodontitis?
how soon does the salivary pedicle form after cleaning?
what are 2 early colonizers?
streptococci and actinomyces
cell-cell recognition when all cells are suspended in solution. clumps form and then attach to the pedicle
interactions between suspended and adhering microbes.
what effect does lactose have on Co-adhesion?
increased lactose = decreased co-adhesion
which species serves as a bridge between early and late colonizers?
list 4 results of increased thickness of a biofilm
- 1. difficulty in diffusion
- 2. oxygen gradient develops
- 3. anaerobic deep layers
- 4. reverse gradients of fermentation products
what is the difference in nutritional needs between supra and subgingival plaque?
- Supragingival: dietary products are dissolved in saliva
- Subgingival: periodontal tissues and blood serve dietary needs
The matrix of the biofilm is composed of what 3 things?
- 1. dead bacterial cells
- 2. saliva
- 3. gingival exudates
what is the backbone of the biofilm?
what are 2 characteristics of supragingival plaque structure?
- 1. mushroom towers: low shear force
- 2. elongated colonies: high shear force
Describe the Gm+ bacterial matrix
fibrillar due to dextrans and levans
Describe the Gm- bacterial matrix
tri-laminar vesicles, endotoxins and proteolytic enzymes
what 2 carbs are involved with the bacterial matrix?
dextrans and fructans
how are the bacterial layers in subgingival plaque near the sulcular epithelium different from the layers from the tooth attached?
no interbacterial matrix and more spirocetes and flagellated bacteria
list 3 advantages of living in a biofilm
- 1. defense: concentrated bacterial enzymes
- 2. protection from external change: minimal diffusion = antibiotic resistance; protection from friction and shearing forces
- 3. transfer of genetic material
list 4 examples of antibiotic resistance in biofilms
- 1. biofilm bacteria more resistant to antibiotics than planktonic
- 2. grow slower and make more exopolymers
- 3. exopolymers retard diffusion
- 4. extracellular enzymes inactivate antibiotics
define dental calculus
mineralized plaque covered by a layer of visible plaque
how is calculus related to periodontitis?
represents a secondary product of infection, not a primary cause
describe supragingival calculus
- 1. coronal to gingival margin
- 2. easily detached
- 3. found opposite salivary ducts
describe subgingival calculus
- 1. hard, dense
- 2. extends to base of pocket but does not reach JE
- 3. in recession subgingival calculus becomes supragingival calculus
list/define the 4 components that make up calculus
- 1. Brushite: basis for supragingival calculus and seen in <2 week old calculus
- 2. Octa Calcium Phosphate: predominant in exterior layers
- 3. Hydroxyapatite: predominant in inner layers of old calculus
- 4. Whitlockite: most common form in subgingival calculus